A prototype solar desalination system (SODESAL) with a parabolic-trough solar concentrator (PTSC) and evacuated tube was designed and analyzed to determine the solar thermal capabilities for small-scale distillation and energy generation. A proof-of-concept study verified that distillation is possible with the system as designed, however a rupture occurred in the copper heat-pipe heat exchanger due to overheating. The internal temperatures of an aluminum heat transfer fin were measured inside an evacuated tube typically used in solar water heater systems to understand the lateral heat distribution and identify possible causes of the rupture. Solar radiation was measured for both the summer and winter solstices to understand the relationship between incident solar radiation and the potential freshwater yield of the system. The lateral heat distribution of the AHTF is dependent upon the PTSC’s solar incident angle. A consistent lateral heat distribution occurred across the AHTF approximately 40 mins after solar noon. The temperature difference between each end of the AHTF can exceed over 225 °C leading up to and following solar noon when the PTSC was set at a static slope. The SODESAL system’s future applications, system improvements and additional research are also discussed along with the capability of small-scale CSP systems.

Uppsatsen berör den komplexa frågan om hur vatten värderas i landskapets ekosystem förhållande som en resurs till människan. Uppsatsen syftar till att undersöka vilka faktorer som är betydande för att ändra attityden till sötvatten och vilka tekniska lösningar, med fokus på avsaltningsanläggningar, som kan vara svaret till framtidens sötvattenproblematik för kustnära städer i Skåne. Genom kvantitativa observationer skapas en giltig teori av ”Skånsk vattenhantering 2120” byggd på generaliseringar av empirin. Därav är uppsatsen av en kvalitativ, induktiv, forskningskaraktär.Genom användningen av scenariometodik presenteras de hot och risker det konventionella vattensystemet kommer utgör för de kustnära städernas ekosystemen och samhällen i Skåne till följd av klimatförändringarna. Vattensystemets karaktär vilket förhindrar vattnet att följa dess naturliga kretslopp i samband med dess otillräckliga kapacitet medför att varken den ekologiska eller sociala dimensionen av hållbar utveckling uppnås. Dem identifierade trenderna för scenariot var: klimatförändringar, befolkning, landskap och vattenanvändning. Den mest betydande trenden visades vara vattenanvändning eftersom den rymmer de mänskliga faktorerna så som konsumtion, attityder och politik. / This paper touch the the complex issue regarding the value of water as a recourse for the ecosystem or for the human. The purpose is to analyse which factors that are of importance for changing the attitude towards freshwater, and what technical solutions, focusing on desalination plants, that can solve the future fresh water issue in the costal cities of Scania, Sweden. Through quantitative observations, a valid theory of "Scania Water Management 2120" is created based on generalizations of empire. Hence the essay holds a qualitative, inductive, research character.By the use of scenario methodology, the climate change effects on the costal cities in Scania will present the threats and risks the conventional water system pose, both for the ecosystem and the society. The systems characteristics which prevent the water from following its natural cycle in combination with its limited capacity entails that neither the ecological nor the social dimension of a sustainable developments is fulfilled. The identified trends for the scenario was: Climate change, Population, the Landscape and Water use. The trend of highest importance was shown to be Water use since it holds the human factors, such as consumption, attitudes and politics.

Transparent exopolymer particles (TEP) have been reported as one of the main factors of membrane fouling in seawater reverse osmosis (SWRO) process. Research has been focused on algal TEP so far, overlooking bacterial TEP. This thesis investigated the effects of coagulation on removal of bacterial TEP/TEP precursors in seawater and subsequent reduction on TEP fouling in ultrafiltration (UF), as a pretreatment of SWRO. Furthermore, the performance of pretreatment (coagulation + UF) has been investigated on a bench-scale SWRO system. TEP/TEP precursors were harvested from a strain of marine bacteria, Pseudoalteromonas atlantica, isolated from the Red Sea. Isolated bacterial organic matter (BOM), containing 1.5 mg xanthan gum eq./L TEP/TEP precursors, were dosed in Red Sea water to mimic a high TEP concentration event. Bacterial TEP/TEP precursors added to seawater were coagulated with ferric chloride and aluminum sulfate at different dosages and pH. Results showed that ferric chloride had a better removal efficiency on TEP/TEP precursors. Afterwards, the non-coagulated/coagulated seawater were tested on a UF system at a constant flux of 130 L/m2h, using two types of commercially available membranes, with pore sizes of 50 kDa and 100 kDa, respectively. The fouling potential of coagulated water was determined by the Modified Fouling Index (MFI-UF). Transmembrane pressure (TMP) was also continuously monitored to investigate the fouling development on UF membranes. TEP concentrations in samples were determined by the alcian blue staining assay. Liquid chromatography-organic carbon detection (LC-OCD) was used to determine the removal of TEP precursors with particular emphasis on biopolymers. Finally, SWRO tests showed that TEP/TEP precursors had a high fouling potential as indicated by MFI-UF, corresponding to the TMP measurements. Coagulation could substantially reduce TEP/TEP precursors fouling in UF when its dosage was equal or higher than 0.2 mg Fe/L. The flux decline experiments showed that coagulation + UF pretreated water had a smaller fouling potential than MF pretreated water. This thesis also provides useful and practical information on controlling bacterial TEP/TEP precursors fouling in UF and RO systems.

abstract: Zwitterionic polymers, due to their supurior capability of electrostatically induced hydration, have been considered as effective functionalities to alleviate bio-fouling of reverse osmosis (RO) membranes. Bulk modification of polysulfone-based matrices to improve hydrophilicity, on the other hand, is favored due to the high membrane performance, processibility, and intrinsic chlorine resistance. Here a novel synthetic method was demonstrated to prepare zwitterionic poly(arylene ether sulfone) (PAES) copolymers, which was blended with native polysulfone (PSf) to fabricate free-standing asymmetric membranes via non-solvent induced phase separation process. Both the porosity of the support layer and surface hydrophilicity increased drastically due to the incorporation of zwitterion functionalities in the rigid polysulfone matrix. The water permeance and antifouling ability of the blend membranes were both remarkably improved to 2.5 Lm−2 h−1 bar−1 and 94% of flux recovery ratio, respectively, while salt rejection remained at a high level (98%) even under the high exposure to chlorine (8,000 ppm•h). Besides the preliminary blended membrane design, for the future membrane property enhancement, this dissertation also focused on polymer structure optimizations via elucidating the fundamentals from two perspectives: 1). Synthetic reaction kinetics and mechanisms on polycondensation of PAES. Interestingly, in combination of experiments and the computational calculations by density functional theory (DFT) methods in this work, only the aryl chlorides (ArCl) monomer follows the classical second-order reaction kinetics of aromatic nucleophilic substitution (SNAr) mechanism, while the kinetics of the aryl fluorides (ArF) reaction fit a third-order rate law. The third order reaction behavior of the ArF monomer is attributed to the activation of the carbon-fluorine bond by two potassium cations (at least one bounded to phenolate), which associate as a strong three-body complex. This complex acts as the predominant reactant during the attack by the nucleophile. 2). Optimized copolymer structures were developed for controlled high molecular weight (Mw ~ 65 kDa) and zwitterionic charge content (0~100 mol%), via off-set stoichiometry during polycondensations, following with thiol-ene click reaction and ring-opening of sultone to introduce the sulfobetaine functional groups. The structure-property-morphology relationships were elucidated for better understanding atomic-level features in the charged polymers for future high-performance desalination applications. / Dissertation/Thesis / Doctoral Dissertation Chemical Engineering 2019

Microbial desalination cells (MDCs), a recent technological discovery, allow for simultaneous wastewater treatment and desalination of saline water with concurrent electricity production. The premise for MDC performance is based on the principles that bioelectrochemical (BES) systems convert wastewaters into treated effluents accompanied by electricity production and the ionic species migration (i.e. protons) within the system facilitates desalination. One major drawback with microbial desalination cells (MDCs) technology is its unsustainable cathode chamber where expensive catalysts and toxic chemicals are employed for electricity generation. Introducing biological cathodes may enhance the system performance in an environmentally-sustainable manner. This study describes the use of autothrophic microorganism such as algae and Anammox bacteria as sustainable biocatalyst/biocathode in MDCs. Their great potential for high valuable biomass production combined with wastewater treatment presents these systems as a viable option to replace expensive/unsustainable catalysts for oxygen production in MDCs. Since alga is a photosynthetic microorganism, the availability of light as well as the electron-donating anodic process may have significant effects on the biocathode performance. A series of experiments evaluating these effects proved that algae perform better under natural light/dark cycles and that higher COD concentrations do not necessarily improve the power density. Furthermore, three different process configurations of photosynthetic MDCs (using Chlorella vulgaris) were evaluated for their performance and energy generation potentials. Static (fed-batch, SPMDC), continuous flow (CFPMDC) and a photobioreactor MDC (PBMDC, resembling lagoon type PMDCs) were developed to study the impact of process design on wastewater treatment, electricity generation, nutrient removal, and biomass production and the results indicate that PMDCs can be configured with the aim of maximizing the energy recovery through either biomass production or bioelectricity production. In addition, the microbial community analysis of seven different samples from different parts of the anode chamber, disclosed considerable spatial diversity in microbial communities which is a critical factor in sustaining the operation of MDCs. This study provides the first proof of concept that anammox mechanism can be beneficial in enhancing the sustainability of microbial desalination cells to provide simultaneous removal of ammonium from wastewater and contribute in energy generation.

This study examines the relationship between oil supply and water security in the Middle East and North Africa. The aim is to see if countries without oil have a harder time mitigating water scarcity, as well as if countries with oil can be expected to become more vulnerable when oil becomes scarcer. This is important considering water security has impacts on many issues, such as political stability and food security. The study looks at panel data for 4 years between 1997- 2012 in a regression with Year Fixed Effects and finds that there is a positive correlation between oil supply and water supply. The study then uses this result to look qualitatively at three countries (Jordan, Bahrain, Saudi Arabia) that are diverse with respect to oil supply, and the results show that oil mainly impacts water security through desalination capabilities, due to oil fueling these facilities. The results also show that desalination may have led to excessive use in some countries, and that oil has allowed a higher consumption of water than is sustainable in the long run. This is significant because it has implications on future water security in the region, and therefore possibly on issues such as political stability.

Water scarcity is set to become a big challenge in the 21st century and more efficient desalinationtechnologies will be needed in the future. In this project, one desalination method called capacitivedeionization (CDI) is explored and we used a model called the ELC model to simulate CDI withComsol. The goal of this project focuses on evaluating the performance of CDI and how changingdifferent operational parameters of the process affects other aspects of desalination. Some examplesare power consumption, desalination rate and water usage. With the gathered information, the process of CDI can be optimized in some way. Even though our project simulates a specific model ofCDI, the hope is to have come to general conclusions regarding CDI so that the results can be usedfor other models. If the correlations between parameters are known, it will be easier to calibrate anysetup of CDI. The gathered data is exported, stored, processed, and plotted using Matlab functionsintegrated with Comsol. The results consist of two sets, the first for constant voltage and the secondfor constant current. Both have results on how desalination rate and energy efficiency are related toparameters such as internal voltage intervals controlling how long the desalination cycle is running,external voltage, and inflow salt concentration in the water. The key conclusions drawn are as thefollowing for constant voltage. High external voltages are effective in increasing both desalinationrate and energy efficiency but will degrade the CDI electrodes. The internal voltage span should bepretty long with high max internal voltage and the minimum internal voltage the same as the external voltage. The energy efficiency increase with lower salt concentrations in the inflow water up toa point. The best setup for the desalination rate is at quite a high maximum internal voltage withvaried low minimum internal voltage. For constant current, low current is generally efficient, whilethe maximum external voltage depends on the current. Avoid a high current with a low externalvoltage. By relating all these parameters, we get more insights into what an energy-efficient and fastadsorbing CDI setup looks like.

This thesis project investigates the configuration of an enclosed evaporation chamber with the intention of converting seawater into potable freshwater. The evaporation chamber's sole heat source is provided by a Fresnel lens, located above the chamber, which concentrates sunlight onto a 3-inch diameter focal plate built into the core of the chamber. The design of the evaporation chamber is modeled after a solar still and is coupled with a heat exchanger to boost efficiency of the system. The chamber was designed with the objectives of being portable, lightweight, low cost, corrosion resistant, interchangeable, and size convenient with the goal of producing 1 Liter of freshwater per hour of operation. The evaporation chamber consists of two primary components, a core and an attached arrangement of fins, all of which are heated via the Fresnel lens. A consistent intake of 2 grams/second of saltwater enters from the top of the chamber and is then gravity fed across the fins. Fin orientation has been designed to inhibit the flow rate of water within the chamber, maximizing the surface area of contact with the heated fins. The evaporation chamber was modeled through SOLIDWORKS and underwent a physical optimization study to reduce material usage while maximizing potential for heat transfer and minimizing fluid flow rate. A symmetric profile of one quarter of the chamber was then simulated in COMSOL Multiphysics. Concentrated solar heat flux through a Fresnel lens was applied to the receiver on the top of the core. The simulation was split into a preheating and an evaporation phase. A profile approximation for the fluid flow was modeled by the CFD module. Following computer simulations, the evaporation chamber was constructed and tested.

Access to clean water is one of the world's foremost challenges that has been addressed on a large scale by membrane-based separation processes for the last six decades. Commercial membrane technology within one operation, reverse osmosis, has remained consistent since the late 1970s, however within the last two decades, access to nanotechnology has created a realm of study involving thin film nanocomposite (TFN) membranes, in which nanoparticles are incorporated into existing membrane designs. Desirable properties of the nanoparticles may positively impact qualities of the membrane like performance, anti-fouling behavior, and physical strength. In the present work, two types of nanoparticles have been evaluated for their potential as TFN additives: cellulose nanocrystals (CNCs) and metal-organic framework (MOF) nanorods. CNCs were chosen due to their high aspect ratios, mechanical strength, and potential for surface functionalization. MOF nanorods are also of interest given their aspect ratios and potential for functionalization, but they also possess defined pores, the sizes of which may be tuned with post-synthetic modification. Both CNCs and MOF nanorods were incorporated into TFN membranes via interfacial polymerization, and the resulting membranes were characterized using a variety of techniques to establish their performances, but also to gain insight into how the presence of each nanoparticle might be affecting the membrane active layer formation. A resulting CNC membrane (0.5 wt% loading) exhibited a 160% increase in water flux and an improvement in salt rejection to 98.98 ± 0.41 % compared to 97.53 ± 0.31 % for a plain polyamide control membrane. Likewise, a MOF nanorod membrane (0.01 wt% loading) with a high ratio of acid chain modification exhibited a 95% flux increase with maintained high salt rejection. For the CNCs, the flux increase is attributed to the formation of nanoscale voids along the length of each particle that form during the interfacial polymerization. These nanochannels introduce new rapid water transport pathways within the active layer of each membrane while maintaining ion rejection. The proposed mechanism for the MOF nanorods also introduces nanochannels into each membrane, but the presence of each nanorod's pore structure may offer another transport pathway for water molecules, one that varies with pore size. In combination, these results have allowed the study of molecular transport of water molecules and various ion species within the active layer of a thin film composite RO membrane. Understanding these phenomena will allow the development of smarter membrane materials to address present-day and future separations challenges. Carbon nanotubes are also demonstrated as surface modifiers for forward osmosis (FO) membranes to address issues unique to the FO process, namely reverse solute flux (RSF). This method shows promise, as a coating density of 0.97 g/m2 reduced RSF for many draw solution species, including a 55% reduction for sodium chloride. / Doctor of Philosophy / Access to clean water is one of the world's foremost challenges that has been addressed on a large scale by membrane-based separation processes for the last six decades. Commercial membrane technology within one operation, reverse osmosis, has remained consistent since the late 1970s, however within the last two decades, access to nanotechnology has created a recent realm of study in which nanoparticles are incorporated into existing membrane designs. It is desired to use nanotechnology, or nanoparticles to improve membrane performance, i.e. create a membrane with better rejection of unwanted ions or contaminants or improve the amount of water that passes through the membrane. In the present work, two types of nanoparticles have been evaluated for their potential as TFN additives: cellulose nanocrystals (CNCs) and metal-organic framework (MOF) nanorods. Both CNCs and MOF nanorods were incorporated into membranes and the resulting membranes were characterized using a variety of techniques to establish how the nanoparticles affected performance. A resulting CNC membrane (0.5 wt% loading) exhibited a 160% increase in water flux (the amount of water passing through an area in a given amount of time) and an improvement in salt rejection. Likewise, a MOF nanorod membrane with a high ratio of acid chain modification exhibited a 95% flux increase with maintained high salt rejection. For both the CNCs and the MOFs, these performance changes are attributed to new pathways within each membrane for water flow that exist due to the presence of the nanoparticles in each system. In combination, these results have allowed the study of transport of water molecules and various ion species in each membrane. Understanding these results will allow the development of smarter membrane materials to address present-day and future separations challenges.

Yes / Fresh water is crucial for life, supporting human civilizations and ecosystems, and its production is one of the global issues. To cope with this issue, we evaluated the performance and cost of a solar-powered direct contact membrane distillation (DCMD) unit for fresh water production in Karachi, Pakistan. The solar water heating system (SWHS) was evaluated with the help of a system advisor model (SAM) tool. The evaluation of the DCMD unit was performed by solving the DCMD mathematical model through a numerical iterative method in MATLAB software®. For the SWHS, the simulation results showed that the highest average temperature of 55.05 ◦C and lowest average temperature of 44.26 ◦C were achieved in May and December, respectively. The capacity factor and solar fraction of the SWHS were found to be 27.9% and 87%, respectively. An exponential increase from 11.4 kg/m2 ·h to 23.23 kg/m2 ·h in permeate flux was observed when increasing the hot water temperatures from 44 ◦C to 56 ◦C. In the proposed system, a maximum of 279.82 L/day fresh water was produced in May and a minimum of 146.83 L/day in January. On average, the solar-powered DCMD system produced 217.66 L/day with a levelized water cost of 23.01 USD/m3 / This research was funded by the Researcher’s Supporting Project Number (RSP-2021/269), King Saud University, Riyadh, Saudi Arabia.